hacking stats would take away some joy of rpgs for me. Even if combat is often messy, I still enjoy seeing my character improve. In Deus Ex when you start, melee weapons and pretty much shit and if you want to play stealth, you have to use the stun prod that has limited ammo. When you pump that stat up, you get to the point where you can take out enemies by whacking them in the back once with a baton. Plus not being master of everything makes you focus on a certain play style, which is part of that whole role playing aspect of it.
Combat in Fallout 3 was fine, I thought. I mostly got through the game by using VATs on faces, or going up close with a shotgun. I like what they're doing with New Vegas. Sounds like there are enemies that don't all succumb to bullet to the face. Different types of weapons and areas you shoot will matter now. Also, I think hardcore mode and adding weight to ammo will effect things. Btw, The non-lethal option doesn't sound like it changes combat at all. You use boxing gloves instead of fisto and a bean bag shotgun instead of regular ammo.